Díselo is a powerful command that means 'Tell it to him/her'. It's a fantastic example of how Spanish can attach pronouns directly to verbs, packing a whole sentence's worth of meaning into a single word.
It's formed from di (the command 'tell'), se ('to him/her'), and lo ('it'). In this emotional song, the singer is pleading with a friend to pass a message to an ex because they don't dare to do it themselves, making Díselo the central, desperate plea of the chorus.
Have you ever been too stubborn or too scared to text an ex, even when you're completely miserable without them? That is the exact mess Puerto Rican singer Jay Wheeler and Zhamira Zambrano unpack in "Dícelo". Instead of talking directly, both singers ask a mutual friend to pass along a message because neither has the courage to reach out first: "Y ya que yo no me atrevo, tú le tienes que decir" ("And since I don't dare, you have to tell them"). Both are hurting, admitting "me duele el cora" (short, casual slang for "my heart hurts"), but pride keeps their phones down.
The song hits hard because the details are so everyday and relatable. Jay sleeps stuck on the right side of the bed ("duermo del lado derecho de la cama") and suddenly realizes he is terrified of flying without her by his side. Meanwhile, Zhamira stays up until sunrise wondering how that TV show ended that they started watching together on the couch ("cómo terminó esa serie que empezamos aquella noche en el sofá"). The ultimate punchline is that both leave the front door unlocked for each other ("está la puerta abierta por si vuelve a donde mí"), suffering from the exact same loneliness while asking someone else to break the ice.